Creating user-defined functions
193
You might call the function with argument names, as follows:
<cfoutput>
Interest: #TotalInterest(principal=Form.Principal, annualPercent=Form.Percent,
months=Form.Months)#
</cfoutput>
Creating user-defined functions
You can use tags or CFScript to create a UDF. Each technique has advantages and disadvantages.
Creating functions using CFScript
You use the
function
statement to define the function in CFScript. CFScript function
definitions have the following features and limitations:
•
The function definition syntax is familiar to anyone who uses JavaScript or most programming
languages.
•
CFScript is efficient for writing business logic, such as expressions and conditional operations.
•
CFScript function definitions cannot include CFML tags.
The following is a CFScript definition for a function that returns a power of 2:
<cfscript>
function twoPower(exponent) {
return 2^exponent;
}
</cfscript>
For more information on how to use CFScript to define a function, see
“Defining functions in
CFScript” on page 198
.
Creating functions using tags
You use the
cffunction
tag to define a UDF in CFML. The
cffunction
tag syntax has the
following features and limitations:
•
Developers who have a background in CFML or HTML, but no scripting or programming
experience will be more familiar with the syntax.
•
You can include any ColdFusion tag in your function definition. Therefore, you can create a
function, for example, that accesses a database.
•
You can embed CFScript code inside the function definition.
•
The
cffunction
tag provides attributes that enable you to easily limit the execution of the tag
to authorized users or specify how the function can be accessed.
The following code uses the
cffunction
tag to define the exponentiation function:
<cffunction name="twoPower" output=True>
<cfargument name="exponent">
<cfreturn 2^exponent>
</cffunction>
For more information on how to use the
cffunction
tag to define a function, see
“Defining
functions using the cffunction tag” on page 200
.
Содержание COLDFUSION MX 61-DEVELOPING COLDFUSION MX
Страница 1: ...Developing ColdFusion MX Applications...
Страница 22: ...22 Contents...
Страница 38: ......
Страница 52: ...52 Chapter 2 Elements of CFML...
Страница 162: ......
Страница 218: ...218 Chapter 10 Writing and Calling User Defined Functions...
Страница 250: ...250 Chapter 11 Building and Using ColdFusion Components...
Страница 264: ...264 Chapter 12 Building Custom CFXAPI Tags...
Страница 266: ......
Страница 314: ...314 Chapter 14 Handling Errors...
Страница 344: ...344 Chapter 15 Using Persistent Data and Locking...
Страница 349: ...About user security 349...
Страница 357: ...Security scenarios 357...
Страница 370: ...370 Chapter 16 Securing Applications...
Страница 388: ...388 Chapter 17 Developing Globalized Applications...
Страница 408: ...408 Chapter 18 Debugging and Troubleshooting Applications...
Страница 410: ......
Страница 426: ...426 Chapter 19 Introduction to Databases and SQL...
Страница 476: ...476 Chapter 22 Using Query of Queries...
Страница 534: ...534 Chapter 24 Building a Search Interface...
Страница 556: ...556 Chapter 25 Using Verity Search Expressions...
Страница 558: ......
Страница 582: ...582 Chapter 26 Retrieving and Formatting Data...
Страница 668: ......
Страница 734: ...734 Chapter 32 Using Web Services...
Страница 760: ...760 Chapter 33 Integrating J2EE and Java Elements in CFML Applications...
Страница 786: ...786 Chapter 34 Integrating COM and CORBA Objects in CFML Applications...
Страница 788: ......
Страница 806: ...806 Chapter 35 Sending and Receiving E Mail...